I don't believe I have any 2-56 whatsoever but I do have 4-40. Any particular head style or bolt length you are looking for? I don't have alot of 4-40 stuff but I do have a small pill bottle of some so far
I bought a bunch of stuff from an old retired airline mechanic/technician. He asked if I could use any bolts or screws and I said "always", and then he showed me his stash!
It was only sort of organized and the guy never threw away a single screw or nut even when he should have. The sorting I've been doing has been a bit overwhelming, just sorting out useable from the junk let alone the zillion different styles of bolts and screws.
Here's an interesting style fastner.... either countersunk or just flat on the "head" end but on the threaded end there is a hex socket. I imagine these are meant to hold something like sheet metal to a frame member where a big faster end on the surface would not be acceptable.